1. Technical Field
The present disclosure relates to an image forming apparatus and an image forming system which includes a duplex printing mode. The image forming apparatus and the image forming system include, for example, a copier, a printer, a facsimile machine, or a multifunction peripheral having at least two of copying, printing, facsimile transmission, plotting, and scanning capabilities.
2. Description of the Related Art
Image forming apparatus such as printers, digital copiers, facsimiles and multifunctional peripherals (capable of serving at least two of the following functions: printer, copier and facsimile), generally include a sheet feeding device, a sheet conveyance device and an image forming unit. The sheet feeding device feeds a sheet to a sheet conveyance path. The sheet conveyance device conveys the sheet along the sheet conveyance path. The image forming unit outputs an image on the sheet. The sheet conveyance path of the sheet conveyance device includes a plurality of conveyance rollers thereon. The conveyance rollers are rotationally driven by drive sources such as motors to convey the transfer sheet.
Such image forming apparatuses can be provided with a registration device which adjusts the sheet position relative to an image position in a direction perpendicular to a sheet conveying direction. The sheet position in the direction needs to be corrected at an upstream side from a position in which the image is output on the sheet so that the image can be formed on an accurate position of the sheet in the direction. This correction of position in the direction is hereinafter referred to as a side registration correcting operation.
It is an object of the present disclosure to accurately correct relative positions of images formed on both faces of a sheet when the image forming apparatus includes a duplex printing mode.